Cutoff table with means automatically controlling position of rolls relative to torch



CUTOFF TABLE WZTH MEANS AUTOMATICALLY CONTROLLING POSITION OF ROLLS RELATIVE TO TORCH u 9. was A. MICHELSQN 3.462.134

Filed March 22 1967 5 Sheets-Sheet 1 INVENTOR.

ANATOL MICHELSQN TTORNEYS,

g 19, 1969 A. MICHELSON 7 3,

CUTOFF TABLE WKTH MEANS AUTQMATICADLY CONTROLLING POSITION 7 OF ROLLS RELATIVE TO TORCH Filed March 22, 1967 5 Sheets-Sheet 2 N I INVENTOR. 9. ANATOL MIQHELSON AT ORNEYS.

Aug. 19, 1969 A. MICHELSON 3,462,134

TH MEANS AUTOMATICALLY CONTROLLING POSITION OF ROLLS RELATIVE TO TORCH CUTOFF TABLE WI Filed March 22, 1967 5 Sheets-Sheet 5 N w m mL N WE VH 0 mm T M T A L m r m A W US. Cl. 266-23 3 Claims ABSTRACT OF THE DISCLOSURE This disclosure pertains to the art of cutting metal slabs and billets of predetermined length from a continuously cast strand and particularly to a table for supporting th billet while being separated from the moving strand. The table comprises a plurality of longitudinally spaced interconnected support rolls having wheels at each end which are guided by parallel rails extending along opposite sides of the table. The rolls are pulled along the rails at a speed equal to the withdrawal speed of the continuously cast strand during the cutting operation so that there is no relative movement between the rolls and strand. In the event the rolls are in an improper position relative to the strand and a cutting apparatus before cutting commences, the rolls are moved longitudinally relative to the strand until the proper position is attained. For this purpose an electrical sensor is provided for detecting the position of each roll relative to the cutting apparatus and a two speed transmission is controlled by the sensor to automatically bring about the required repositioning of the rolls.

The present invention is directed toward the cutting art and, more particularly, to a conveyor and associated cutting apparatus.

The invention will be described in particular with reference to a cutoff table intended for use as part of the terminal equipment associated with a continuous slab casting machine. Usually in such an arrangement, a gas fired cutting torch is mounted so that the torch moves longitudinally with the strand while traversing across it to cut off the prescribed length of billet. However, the invention may be suited to other applications wherever the repositioning of support elements beneath a member is desirable to prevent damage to the elements owing to a processing step which the member is about to undergo.

Present day continuous casting machines commonly employ a continuous casting mold in an elevated posi tion above the plant floor which cast a strand of metal vertically downward. Withdrawal rolls positioned along the path of advance of the strand first bend it while still hot from a vertical to horizontal position and then straighten it, after which the strand moves off in a horizontal direction through the terminal equipment.

Heretofore, cutoff tables have included a series of rolls supporting the strand in its horizontal position which at the start and during cutting, move regardless of the cutting torch position. Often as not, the roll position and cutting torch will coincide when cutting commences resulting in damage to the rolls.

These and other difficulties are overcome in the present invention by providing that the support rolls upon which the strand and billet rest during the cutting operation are self adjustable relative to the position of the cutting torch and billet so as to reposition the series of rolls before cutting commences thereby avoiding damage to the rolls from exposure in the flame and spark sector of the torch.

In accordance with the invention, a continuously mov- United States Patent 3,462,134 Patented Aug. 19, 1969 ice ing strand which is to be cut periodically into predetermined lengths is supported on a series of longitudinally spaced support rolls movable in the direction of strand movement. A member which interconnects each roll in fixed spacial relationship is capable of movement at a speed equal to the linear speed of the strand and also at a differential speed. Each roll is freely rotatable relative to the interconnecting member and the strand, and subject to the relative speeds of the interconnecting membet and the strand, remains motionless beneath the strand or is displaced longitudinally to a different support position relative to the strand. A sensor is positioned in the path of the rolls for detecting the position of each roll relative to a reference plane which is moving at the same linear speed as the strand. A drive source for the interconnecting member is controlled by the sensor to move the rolls at the differential speed until repositioned relative to the reference plane.

Further in accordance with the invention, where the strand is a continuously cast slab of metal, the location of the reference plane is defined by a cutting torch mounted on a carriage adapted to move with the slab once cutting commences. During the cutting operation, the torch also moves transversely of the strand and the rolls are repositioned so that the pitch between the rolls is greater than the angle of the flame and spark sector of the torch at the level of the rolls.

Further in accordance with the invention, the interconnecting member comprises a plurality of chain links each of which carries a contact plate, which in the proper support position of the rolls relative to the reference plane, engages the sensor to permit the cutting operation to commence.

Accordingly, it is among the objects of the invention to provide a plurality of longitudinally spaced movable support elements which can be repositioned in relation to the supported object.

A further object is to provide a horizontal cutoff table for supporting heavy billets and slabs which are cut periodically from the end of the continuously cast metal strand.

A further object is to provide a cutoff table composed of a series of rolls each of which rests on wheels pulled by a continuous chain conveyor in which the Wheels and rolls are rotatable relative to the chain.

These and other objects will become more apparent by referring to the following description and drawings wherein:

FIGURE 1 is a side view of a cutoff table constructed in accordance with the preferred embodiment of the invention;

FIGURE 2 is a partial cross sectional view through one of the support rolls of the cutoff table shown in FIGURE 1;

FIGURE 3 is a sectional view of a two speed transmission employed in the drive for the support rolls;

FIGURE 4 is a schematic showing the limit in cutting torch positions relative to the pitch of the support rolls;

FIGURE 5 is an electrical schematic diagram depicting a control circuit for the cutoff table.

Referring now to the drawings wherein the figures are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting same, in FIGURES 1 and 2 are shown a cutoff table 10 composed of a plurality of longitudinally spaced support rolls 12, each of which is mounted on wheels 14 at the opposite ends which roll on upper and lower parallel rails 15, 16 extending in a longitudinal direction on opposite sides of a continuous metal strand 17 advancing from the left as shown in FIGURE 1. The rolls 12 have a pitch line 18 which coincides with that of the rolls of the withdrawal conveyor (not shown) which brings the strand 17 down from the continuous casting mold so that the strand 17 moves onto the cutoff table without change in elevation. The wheels 14 and upper rails 15 are intended to guide the rolls 12 and assume the entire load of the strand 17 and transmit it to a frame 20. A shaft extension 21 from opposite ends of each roll 12 supports each wheel 14 on a bushing 22. A second shaft extension 24 of reduced diameter extends outwardly from the end of each shaft extension 21 and supports a chain link 26 on a bushing 27. The links 26 are interconnected so as to form a continuous chain conveyor 28 on each side of the rolls 12, each of which is driven by two pairs of longitudinally spaced sprockets 30, 31 for pulling the rolls 12 along the rails 15, 16. Thus, each roll 12 can rotate freely relative to the strand 17 and conveyor chain 28.

In accordance with the preferred embodiment of the invention the pair of sprockets 31 is mounted on a shaft 32 which is shown in FIGURE 3 as being driven by a drive sprocket 33 which may be connected to the power source of the withdrawal rolls of the continuous casting machine. A transmission 35 between the drive sprocket 33 and shaft 32 is alternately coupled by means of a throw out bearing 37 to drive the shaft 32 at a 1 to 1 ratio with reference to the drive sprocket 33 or at an increased speed ratio of say 5 to 1. With the throw out bearing 37 in the position shown in FIGURE 3, the gear train for the transmission 35 includes rotatable gear 38 which meshes with step up gears 39, 40 journaled on a counter shaft 41 for driving gear 42 fixed on the shaft 32. The coupling between drive sprocket 33 and shaft 32 is thus made through gears 38, 39, 40 and 42 for driving at increased speed. Alternatively with the throw out bearing 37 shifted to the right, the coupling is made at 45 between the drive sprocket 33 and the shaft 32 for driving the shaft directly. The throw out bearing 37 is remote controlled by a solenoid operated mechanical linkage 47 in a manner to be described hereinafter.

Referring again to FIGURES 1 and 2, a cutting torch carriage 50 is shown mounted on wheels 52 which roll on parallel rails 53 extending longitudinally on opposite sides of the cutoff table 10 in an elevated position for supporting the carriage from each end. The carriage 50 forms no part of the invention and it will be understood by those familiar with such cutting torch apparatus that it is used in association with terminal equipment for periodically cutting off a predetermined length of the strand 17. The carriage 50 moves with the strand 17 by virtue of a pair of clamps 55 which are actuated to grip the opposite sides of the strand 17 as it is moving therebetween causing the carriage to be drawn along by the strand. A pair of cutting torch units 56 is mounted on an overhead trackway of the carriage 50. Each torch 56 is adapted to be traversed from the side inwardly toward the center of the strand 17 simultaneously so that the cutting is in a transverse reference plane which moves longitudinally at the same linear speed as the strand 17 To avoid accumulation of metal splash and to effect easy removal of splash, a trough 60 (FIG. 2) extends longitudinally and transversely beneath the rolls 12 between rails 15 and has an inclined bottom 62 which is constantly sprayed with water from nozzles 63 extending along one side of the trough 60 so that high velocity water constantly splashes the bottom 62 to wash away accumulations of metal into a container positioned beneath the outlet 64.

To cool the rolls 12 a second trough 65 extends longitudinally and transversely beneath the rolls between rails 16. A longitudinally extending rubber strip 66 is positioned in the bottom of the trough 65 which contacts the rolls on their return course on rails 16. The rolls move through water in the trough 65 which is continuously circulating. The rolls are rotated by frictional contact with the strip 66 and are therefore kept uniformly cool in the water bath. For slack adjustments of the conveyor chains 28, the driven sprocket 30 is mounted at each end in a longitudinally adjustable mechanism 70 (FIG. 1).

Consider now that a billet of predetermined length is to be cut from the end of the continuously moving strand 17 by means of the cutting torches 56 and assume, as in the prior art, that at the start of cutting, the support rolls 12 were moving beneath the torches 56 without regard to the position of cut; then it would often occur that the rolls would be found to lie within the flame and spark sector of the torches resulting in damage to the rolls.

In accordance with the invention, the rolls 12 are pulled along by the conveyor chains 28 at the speed of advance of the strand 17 so that there is no relative rotation between the rolls 12 and strand 17. When the strand 17 has advanced the distance L (FIG. 1), whichis the prescribed billet length with reference to the extreme left position of the carriage 50, then account must be taken of the position of the rolls 12.

In accordance with the preferred embodiment of the invention a limit switch is adapted to be actuated by a spring biased lever arm 76 extending into the path of the strand 17 as shown in FIGURE 2. Switch 75 is mounted on adjustable bracket 78 which is releasably clamped to a longitudinally extending web 79 so as to be able to vary the distance L which determines the billet length. A second limit switch 80 is located a distance C in front of the reference plane of the torches 56 (FIG. 1) and is mounted on a bracket 82 extending downwardly from the cutting torch carriage 50 so as to be movable therewith immediately above the conveyor chain 28 (FIG. 2).

Each link 26 at the opposite ends of the rolls 12 carries a flat plate 85 which extends in the direction of movement a distance K (FIG. 1) as determined by the angle of magnitude of the flame and spark sector and by the pitch B between rolls 12, the significance of which will be explained more fully hereinafter. The actuating arm 86 of the limit switch 80 lies in the path of movement of the plates 85 and is positioned in front of the reference plane of cutting torches 56 in effect one half the distance between the leading and trailing edges of adjacent fiat plates 85, or the distance C.

The relationship of the distance C, pitch B and width K will be more fully appreciated by referring to FIG- URE 4 in connection with a description of the operation of cutoff table 10. In an intial position before cutting commences, the torch carriage 50 is at the extreme left position as shown in FIGURE 1. The strand 17 and the rolls 12 as pulled by the chains 28 are moving at the same speed from left to right. During this time the rolls 12 do not rotate and each roll is in point contact carrying its portion of the strands weight. As the end of the strand 17 reaches lever 76 projecting into its path (FIG. 2) the limit switch 75 is actuated and gives a signal to solenoid 92 (FIG. 5) which control the clamps 55 on the cutting torch carriage 50. The carriage commences to move with the strand thus the length of billet which is to be cut is established as soon as the clamps 55 engage. At this moment cutting has not yet commenced.

There are two possible positions in which plates 85 might be found relative to the actuating arm 86 of the limit switch 80; (1) either the rolls 12 are in such position that a plate 85 is beneath the actuating arm 86 closing the switch, or (2) a plate 85 is advancing toward the actuating arm 86 and the switch 80 is open. The latter condition is illustrated in FIGURE 1. The maximum distance from which a plate 85 can approach the switch 80 is equivalent to twice the distance C.

Consider now the second possibility, that is the switch 75 is closed but switch 80 is open. Cutting may not commence since the flame and spark sector will be too near one of the rolls 12. In this case switch 75, besides signaling the closing of clamps 55, also actuates a solenoid 97 (FIG. 5) controlling the mechanical linkage 47 causing the throw out bearing 37 to be shifted into the high speed drive position as shown in FIGURE 3. With the drive now through gear train 38, 39, 40, 42, the shaft 32 of the pair of sprockets 31 is accelerated driving the conveyor chains 28 at say five times the speed of advance of the strand 17. The repositioning of rolls 12 thus commences with a minimum of friction inasmuch as each roll is free to rotate relative to the strand 17, wheels 14 and chain links 26. The differential in speed is maintained until the roll position is such that the next plate 85 closes the limit switch 80. With the closing of limit switch 80 the torches 56 commence to cut and traverse toward the center of the strand 17. As cutting commences the rolls 12 have been repositioned with respect to the cutting torches 56 as shown by the solid line torch position a in FIGURE 4.

Consider now the first condition referred to above in which a plate 85 is already underneath the switch actuating arm 86 closing switch 80. If only switch 80 is closed and not switch 75, then nothing will happen. However, if switch is closed at the moment switch is actuated, then the electrical circuit is such that the mechanical linkage 47 is not actuated and the throw out bearing 37 remains in its normal position continuing to drive the conveyor chains 28 at the withdrawal speed of the strand 17. Cutting may commence immediately since the rolls 12 are already in the proper position relative to the cutting torches 56. After the start of the cutting process, switch 80 is deenergized until the billet which has been cut completely passes beyond switch 75.

The limit which the cutting torches 56 may be displaced at the time cutting commences under the first condition described above is illustrated by the dot-dash torch position b shown in FIGURE 4. The torches 56 thus may initiate cutting at any position between the two extremes shown without doing damage to the rolls 12 which have a pitch B. The limit positions of the torches 56 are thus determined by the width K of the plates in accordance with the angle of magnitude of the flame and spark sector of the torches 56 and the pitch distance B.

Referring now to the FIGURE 5 in more detail, an electrical schematic of the control circuit for the cutoff table 10 is shown. Under the second condition assumed above where switch 75 is closed and switch 80 is open, a power source actuates the solenoid 92 of clamps 55 through lines 93, 94 and 95 and simultaneously the solenoid 97 of the mechanical linkage 47 shifting the drive to high speed for repositioning the rolls 12. As soon as switch 80 is closed a solenoid 98 is actuated through lines 93, 99, 100, opening gas valve 102 to start the torches 56 and simultaneously through line 104 a control relay CR 2 is energized to drop out the solenoid 97 retuming the drive to 1:1 speed ratio. Control relay CR 1 maintains the circuit to the gas valve solenoid 98 so that cutting may continue while at the same time maintaining CR 2 in so that the drive remains 1:1. When the torches 56 have completed cutting,.switch 105 opens to restore the circuit to the initial condition.

Now consider the first condition referred to above in which switch 80 is closed at the time switch 75 is actuated by the end of the billet. In this case the circuit operates as described in the second condition except that the solenoid 97 remains deenergized and the drive remains at 1:1 speed ratio.

Having now described a preferred embodiment of the invention it will be appreciated by those skilled in the art that various modifications and changes may be made in the invention without departing therefrom as defined in the appended claims, the scope of which is intended to include the reasonable equivalents of the structure described herein except insofar as limited by the prior art.

I claim:

1. Apparatus for supporting a continuously moving strand and severing it into predetermined lengths, said apparatus comprising:

a series of rolls linearly spaced a predetermined distance apart for physically supporting a portion of the strand;

guide means extending in the intended direction of strand movement for rotatably supporting each roll;

interconnecting means extending between each roll for joining the series of rolls and permitting rotation of individual rolls relative to the guide means and interconnecting means;

drive means for moving the series of rolls at least two different linear speeds including a first speed equal to the intended speed of the strand and a second speed different from that of the strand such that the rolls can be repositioned by moving longitudinally relative to the strand at a rate determined by the differential in speed;

control means including first means for sensing the position of individual rolls relative to a reference plane moving at the intended linear speed of the strand and second means operable in response to said first means for varying the speed of said drive means wherever the reference plane is within a predetermined distance from any roll;

cutting means positioned in the reference plane for cutting off a length of the strand; and

means for producing movement of the cutting means with the strand during a cutting operation.

2. The apparatus of claim 1 wherein the cutting means is a gas cutting torch.

3. The apparatus as defined in claim 1 including wherein said control means further includes means for preventing operation of said cutting means when said reference plane is within a predetermined distance from one of said rolls.

References Cited UNITED STATES PATENTS 3,322,418 5/1967 Lotz 26623 I. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner US. Cl. X.R. 

